The invention relates to an injector for implanting a (temporarily) folded intraocular lens, with which the folded lens can be inserted in the capsula of the lens of the eye through an opening incision of approx. 3 mm in the eye.
In eye surgery it is very important that the surgical incision through which a cataract is removed and then the required artificial lens is implanted is as small as possible (approx. 3 mm) so that optimum healing is guaranteed and no suture is required. To be able to implant artificial lenses with the required diameter of approx. 5-6 mm, these must be foldable so that they pass through the small incision of 3 mm.
A wide variety of devices are known for folding the lenses and inserting the folded lens with the aid of forceps and also injectors for direct insertion of the lenses in the eye. In the case of the latter, generally the lens which is inserted essentially unfolded is progressively folded axially as it is slid forwards in the injector, or an already folded lens is inserted and only slid out.
Thus, EP 0 503 136 A1, EP 0 497 505 A1, EP 0 402 138 A1, WO 98/25548, WO 94/10912 and DE 40 39 119 C1 for example disclose devices for folding an intraocular lens in a wide variety of embodiments through which the lenses are in each case accordingly folded or prefolded and then inserted in the eye by means of forceps or an injector. This procedure is relatively complex and in addition uncertain due to the handling with the forceps as the folded lens can easily slip out of the forceps.
DE 41 10 278 A1, DE 36 10 925 C2, WO 96/15743, EP 0 270 257 A1, EP 0 477 466 A1, WO 97/113476 and WO 97/15253 disclose lens injectors in which partly prefolded lenses are inserted in the receiving chamber of an inserting cartridge which can be fastened to the front end of the injector. Usually, this cartridge also serves as receiving chamber for safely storing and transporting the lens. After the cartridge is fitted to the handle part of the injector body, the lens is slid through the tapering channel to the outlet end by axial displacement by means of a plunger, through which the lens is folded or folded again. These known injectors are of relatively complex design comprising a large number of individual parts, and the user must assemble at least two separate parts before the lens can be slid out.
WO 97/13476 discloses an injector in which the lens is first folded in a folding instrument and then placed together with the latter radially in the injector. Then, with the aid of a plunger, the folded lens is slid out of the folding device through the tapering delivery cover, through which the lens undergoes further folding. Thus, two instruments are needed here, one for the preliminary folding and one for injecting the folded lens.
WO 98/05281 discloses an injector the lens-holding cartridge of which exhibits at its rearward end a radially swivelling flap with a central holding rib by means of which the unfolded lens is pressed radially into the transporting channel and held there. However, genuine folding of the lens only takes place through the forward sliding movement of the lens through the tapering transporting channel. Thus, this is a relatively complex design with correspondingly complex handling.
In addition, WO 95/07059 and WO 95/13022 describe an injector with a cylindrical transporting channel into which an unfolded lens is slid tangentially with the aid of an independent slider rib not connected to the injector body so that the lens is rolled in the transporting channel. The rolled lens is then slid out by means of an additionally separate cylindrical slider filling the transporting channel completely. Thus, two separate parts have to be introduced into the injector and the lens delivered in a rolled state.
In addition, U.S. Pat. No. 3,123,905 A describes an injector with a cylindrical body and a cylindrical transporting channel which is provided coaxially therein and debouches into a delivery tip which tapers conically. The cylindrical injector body incorporates a relatively narrow radial insertion slot through which the lens placed on the surface of the body over the insertion slot is pressed in with the aid of an independent insertion rib. Apart from the fact that this known injector cannot be used at the same time for transporting and safely storing an unfolded lens, the insertion of the lenses through the very narrow insertion slot is difficult or even impossible since lenses are known to be practically incompressible. In addition, the independent rigid slider also fills the entire cross-section of the transporting channel so that the insertion rib must be removed after insertion of the lens. In addition, the transporting channel tapers conically to a point so that the inserted lens, in cylindrical form in the channel, is rolled up even further when it is slid out, giving major delivery problems.
Lastly, DE 43 03 051 A1 and U.S. Pat. No. 5,190,552 A show an injector in which an unfolded lens is inserted through a radial insertion opening into the transporting channel which is open upwards radially in this section, on to a lens-holding slide. The lens is held securely to prevent it dropping out by means of a lens locking rod which is slid axially over the inserted lens. When slid out, the holding rod and the slide are together slid through an at least initially tapering transporting channel of the injection tube, through which the lens, still held centrally by the holding rod, is folded around this rod. This is also a relatively complex design with relatively complex handling. In addition, the lens must be held securely pressed down in its position in the slide by the locking rod as it is slid forwards so as not to be slid off the slide by the rod.
The object of the invention is to provide an injector of the kind named above which exhibits the simplest possible construction and allows reliable sterile handling during safe storage, transport, folding and implanting of the lenses.
According to the invention, the transporting channel of the one-piece injector body is an axially continuous opening with a constant cross-section. Thus, the transporting channel has a cross-section which is always the same throughout the entire injector, namely from the slider inlet end to the lens delivery end, which represents a simplification in terms of manufacturing. In addition, the supporting surface for the unfolded lens is arranged radially offset upwards in the direction of insertion relative to the transporting channel. As a result of this, the lens is inserted lying above the transporting channel or at least essentially a distance from the bottom of the transporting channel, but at the same time below the upper surface of the body. Lastly, the holding rib or rod holding the unfolded lens on the supporting surface is a radially extending plate-shaped folding rib which is arranged like the die of a stamping tool and can be pressed radially well into the transporting channel or transversely to the transporting direction through the slot-shaped insertion opening. Thus, the folding rib and the body act like a correspondingly embodied mold and die on the lens lying between them and bend this in the middle, at the same time sliding it into the transporting channel in its final folded state. Then, it is only necessary for the lens to be slid forwards in this final folded state in the transporting channel by the slider, which here obviously is also a rod with a constant cross-section.
In a further embodiment of the invention, the one-piece injector body can exhibit a rectangular cross-section overall, i.e. both the thicker insertion and folding part and the thinner injecting part and the transporting channel each exhibit a rectangular cross-section. All these parts, namely the body sections and the transporting channel, can also exhibit a round or oval cross-section or the holding part can be rectangular while the injection tube and the transporting channel exhibit a round cross-section.
Obviously, in its cross-section the transporting channel has to be embodied according to the dimensions of the folded lens. Thus, the width of the channel must be roughly equal to double the thickness of the lens plus the thickness of the folding rib, while the height of the channel should be at least equal to half the diameter of the lens. In addition, it its width in relation to the surfaces surrounding it such as the walls of the transporting channel, the folding rib is embodied so that the cilia of the lens are not jammed and damaged during folding and displacement.
Since the dimensions of the injector are relatively small overall, its components are made so that they partly engage in one another in operation, which is possible through the maximum simplification of the components. After the lens is folded by pressing the folding rib into the transporting channel, the folding rib in fact also remains pressed in, preferably detained, while the folded lens is slid out. Therefore, on its upper side the sliding rod with the constant cross-section exhibits a longitudinal groove which embraces the folding rib in a U-shape with a small sliding tolerance during the longitudinal movement. In addition, it is advantageous when the front side of the slider is embodied matching the shape of the folded lens, i.e. with an inward curve over approximately a quarter cylinder, so that a uniform sliding pressure is exerted on the lens.
To guarantee reliable handling of the injector in its roles as a lens-holding, lens-folding and lens-inserting device, detent and indexing means are provided on the slider, folding flap and body for the four different working end positions.
Thus, three positions are provided for the slider, with corresponding positioning means, namely a first position for determining the slider positions in the position retracted behind the radial insertion opening, a second advanced position in which the folded lens is slid close to the front delivery opening of the injection tube, and lastly a third and final position in which the end face of the slider reaches the outlet opening of the injection tube. The first two positions can be achieved through indexing balls or projections or similar means, while the third position can also be achieved through abutment of the thrust plate provided on the injector body at the outer end of the slider projecting from the injector body.
According to the invention, the preferably round supporting surface for the unfolded lens is divided by the insertion and folding slot into two part surfaces which are aligned horizontally, i.e. parallel to the bottom of the transporting channel and at the same time to the upper side of the injector body. However, these part supporting surfaces can also be aligned inclined inwards in the direction of the transporting channel in the shape of a roof (i.e., V-shaped), preferably at an angle of 30xc2x0 to the horizontal or to the upper side of the body, or inclined at an angle roughly corresponding to the inclination of the lens body. This and additional large transitional radii between the supporting surface parts and the folding slot allow an optimum folding movement.
It is advantageous when longitudinal narrow supporting strips are provided just above the supporting surface, by means of which the lens is placed on the supporting surface under slight tension and which at the same time serve as supporting strips for the stop strips provided on the folding rib or on the corresponding pivoting lever. Thus, these supporting strips also ensure that the lenses are at least held gently.
The folding rib pivotable radially into and out of the transporting channel through the insertion opening is provided at the front end of a pivoting lever articulated pivotably on the upper side of the body. In this case, the upper side of the body holding part can be provided with a correspondingly wide groove in which the pivoting lever is inserted completely without projecting from the surface when pivoted or swung in. However, to allow the pivoting lever to be swung out again, it must be possible to grasp the inserted lever, for example by means of a thrust plate which is provided on the lever over the folding rib and which extends over the entire width of the body, or by other means. However, the lever can also be articulated by means of appropriate pivot lugs on the body so that it lies flat on the body. In this case, these pivot lugs on the body can be opened upwards by means of a narrow slot in a manner known per se, so that the pivot pins can be pressed into the mounting openings by means of these slots. However, such a hinge snap assembly can also be provided in the embodiment of the lever in which it is inserted in the body.
In order to determine the two working positions of the folding rib by means of the lever of the folding rib which can be pivoted through approx. 180xc2x0, corresponding indexing devices are provided on the lever and the body, through which in each case an angular position of the lever is determined for lying on and holding the unfolded lens and for holding the folded lens in the inserted position. This prevents the lever pivoting upwards or exerting insufficient pressure in the holding position or in the folding position with the result that the lens falls out or moves, so that its correct delivery is not assured.
According to one development of the idea of the invention, to facilitate handling and also to fix the injector in a transport container as described further on, a transversely extending grip plate is provided roughly in the middle on both sides of the body holding part. As a result of this, in particular when ultimately delivering the folded lens from the injector or placing this lens in the eye, the injector can be handled in roughly the same way as an injection syringe.
It is particularly advantageous when the injector consisting of only three parts, namely the injector body, slider and flap, is made entirely of transparent plastic, e.g. by injection molding, so that the three injector components are assembled or held together by simply pressing them into or onto one another. Apart from that, the transparent design of the injector allows precise monitoring of the position of the lens. For example it is possible to observe how the unfolded lens is lying, how this is then folded by means of the folding rib when it is pressed into the transporting channel, and then slid forwards by means of the slider and then slid out.
Any error in the positioning of the lens can then be observed at once so that the person handling the injector can adjust his further actions to this circumstance.
Obviously, the injector body can be embodied in two parts for production reasons, with a dividing plane parallel to the transporting channel. After production by injection molding for example, the two body parts are assembled and glued together.
In addition, according to the invention, the slider can be embodied in two parts, being composed of a front longitudinally displaceable part and a rearward rotatable part. The rearward part exhibits a thread which is guided in a threaded bore of the holding part in order to ensure precisely controllable forward movement of the slider and hence of the lens. In addition, retraction of the complete slider assembly can be achieved through known means, such as openings and snap pins on the adjacent end sides of the parts of the slider.
For storing and transporting an injector according to the invention, a receiving container can be used which essentially consists of a sleeve with a cover in which lateral holding plates are provided for positioning the injector by means of its lateral grip plates. The holding plates each have a barb which points in the direction of introduction, which barbs grip over the injector grip plates and hold the injector securely lying on the inner wall of the container. Optimum positioning of the injector in the container is achieved through an axial projection which is provided on the cover and extends to the rearward end face of the injector body when the cover is fitted, or through a slotted spacer tube which is fitted between the rearward end side of the injector body and the rear thrust plate of the slider and in addition through the bearing of the rearward end face of the slider thrust plate on the internal end side of the cover which can be lined with very soft elastic plastic. Thus, even with careless handling of the container, the slider cannot be unintentionally slid forwards in the transporting channel beyond its rear retracted detent position, which could lead to the unfolded lens lying on the supporting surface being pushed off and expelled or even damaged.
The transport container or at least its receiving sleeve can also be made of transparent plastic in a manner know per se, e.g. by injection molding or blow molding, so that it is easy to establish whether the injectorxe2x80x94and the lensxe2x80x94are in the correct position.
The transport container with the injector located in it can be filled with a sterile transport liquid known for safe storage and delivery of folding lenses. In this case, after the introduction of the injector, the container sleeve is filled with the liquid in a vertical position with the opening uppermost. When the cover is fitted, the projection on the cover and/or the inner cover cone displace liquid so that no air remains in the closed container, guaranteeing sterile safe storage of the injector and retention of the elasticity of the lens.
As is general practice with drugs and medical instruments, the transport container for its part can be placed in a packaging carton in which a packing slip is also enclosed, guaranteeing additional protection for the transport container and the injector and ultimately the lens itself.
For folded delivery of an intraocular lens by the injector according to the invention, the pivoting lever covering the radial insertion opening in the injector body is swung back through approx. 180xc2x0, exposing the insertion opening, after which an unfolded lens is inserted and placed on the supporting surface provided at the upper end of the insertion opening. Then, the pivoting lever is swung back again through approximately 180xc2x0 until the underside of its folding rib rests on the upper side of the lens body, if possible with the lever detained in this holding position. Then, in this state the xe2x80x9cloadedxe2x80x9d injector is used or it is inserted and fixed in a transport container and placed in a packaging carton etc. for safe storage for use later or prepared for transport to other locations for use.
When it is to be used during an implant operation, the injector is first removed from a container and the pivoting lever is pressed in radially as far as the stop, e.g. by pressing on its thrust plate with the folding rib located underneath it, so that the folding rib presses the underlying lens off the supporting surface through the folding slot into the transporting channel. At the same time, the lens lies and is folded symmetrically longitudinally elastically around the folding rib and in the process is brought into the folded insertion state. After this, the slider is slid out of its retracted resting position into the second position, through which the lens is brought to its position close to the ejection opening in the transporting channel. Thus, the injector is ready for use for implanting the folded lens located in it.
Then, after the short surgical incision has been made in the eye and the narrow injection tube part of the injector, the tip of which should be embodied so that it tapers into an extremely shallow point for easier introduction, has been introduced into the interior of the eye through the iris just above the lens sac, the injector slider is slid inwards further as far as the end stop, through which the lens is slid out of the tip of the injector into the lens sac. Then, the injector is pulled out and either discarded as a single-use part or placed in safe storage for reloading with an unfolded lens as a multiple-use part.
In the following, the invention is described in greater detail on the basis of a plurality of embodiment examples with reference to the drawing.
In this